1. Field of the Invention
The present invention relates to a method of and a system for predicting the print colors of a print produced by a printing press.
2. Description of the Related Art
Prints are produced by, for example, generating original film plates in various colors including cyan (C), magenta (M), yellow (Y), and black (K), for example, producing PS plates (presensitized plates) from the original film plates by exposure and development, mounting the PS plates on a printing press such as a rotary press or the like, and adjusting printing conditions including the ink film thickness, the dampening water, the temperature, etc.
As described above, complex steps are involved in producing prints. In order to produce a print in desired colors, it has been customary prior to the production of the print to generate a proof sheet using a simple output device such as a monitor, a color printer or the like, and adjust printing conditions in order for the proof sheet to have the desired colors of the print to be produced.
Japanese Laid-Open Patent Publication No. 2007-208492, for example, discloses a method of confirming the colors of a print before the print is produced by a printing press. According to the disclosed method, if the colors of a proof fall in an allowable range with respect to the colors of the print, then the print is produced by the printing press without changing platemaking data for generating PS plates and target densities to be set as printing conditions in the printing press. On the other hand, if the colors of the proof sheet deviate from the allowable range with respect to the colors of the print, then the platemaking data are changed or a target mixed-color halftone density or a target halftone dot area ratio which is a parameter related to the target density as the printing condition, and thereafter a proof sheet is produced again, the process being repeated until the print having the desired colors is produced.
The colors of a print are normally adjusted by the operator who adjusts the ink keys to change the solid densities of the inks, i.e., the densities of monochromatic images at a halftone dot percentage of 100%. The process of changing the densities of the proof sheet by changing the target mixed-color halftone density or the target halftone dot area ratio, and the process of changing the densities of the print using the ink keys tend to cause the operator who makes adjustments to develop different sensations about the colors. Therefore, it is possible that the print having the colors which match the proof sheet will not be produced.
Furthermore, the printing press whose ink keys have been set to target densities may not necessarily produce a print according to the target densities because the printing press has a complex printing mechanism. As a consequence, the densities of a print that is actually produced and the densities of a proof sheet produced for the print may not be in agreement with each other.